This information is relevant to version 1.12 of the bitmap font generator and only useful for 
full conversions.
You can find the bitmap font generator here: 
http://www.angelcode.com/products/bmfont/ (Windows only--lame, i know).
Once you have the program installed and opened, go to 
Options > Font Settings. Choose the font you want to convert and click 
OK (the rest can remain at their defaults).
Now go to 
Options > Export Options. Under 
Presets choose "White text with alpha." For 
Font descriptor choose "XML." For 
Textures choose "DirectDraw Surface." For 
Compression either one will work, but for best quality you're going to want to pick "DXT5." You can leave the rest at their defaults. Click OK.
Now make sure all the characters are selected by going to 
Edit > (Un)Select all chars.
Now all you need to do is go to 
Options > Save bitmap font as... and pick a place to save them at.